The present invention relates to a reciprocating diaphragm pump. More specifically, the present invention relates to a reciprocating diaphragm pump that provides diaphragm breakage prevention and improved intake into a pump chamber.
In reciprocating diaphragm pumps, a diaphragm divides the space inside the pump into a pumped fluid side space and a working oil side space. A piston capable of reciprocating motion is disposed on the working fluid side space. The reciprocating motion of this piston causes, via the working fluid, the diaphragm to move in a reciprocating manner. This causes the pumped fluid to be sucked in to the pumped fluid side space and to be discharged out from the pump, thus providing continuous transfer of the pumped fluid.
When the piston moves backward, the pressure of the working fluid drops, thereby causing the diaphragm to be pulled toward the working oil, making it expand toward the working fluid side. When this happens, an intake valve disposed in an intake flow path that communicates with the pumped fluid side space is opened, and the pumped fluid flows into the pumped fluid side space. Next, when the piston moves forward, the pressure of the working oil increases, causing a force in the direction of the pumped fluid side to be received by the diaphragm, which then deforms in the direction of the pumped fluid side while pushing the pumped fluid. Since the intake valve is closed at the time, the pumped fluid in the pump does not backflow toward the intake flow path and is instead sent out from the pump through a discharge flow path disposed in the pumped fluid side space. By repeating these steps, the pumped fluid is transferred continuously.
In the steps described above, the application of excessive force by the working oil on the diaphragm can cause deformation or damage to the diaphragm. To prevent this, a counter plate (a plate having many thin holes) is generally installed in the space inside the pump to prevent excessive deformation of the diaphragm. Among reciprocating diaphragm pumps, there are those that have counter plates in both the pumped fluid side space and the working oil side space and those that have a counter plate only in the working fluid side space.
With pumps that have counter plates in both the pumped fluid side space and the working oil side space, excessive deformation of the diaphragm in both the intake step and the discharge step is prevented. However, since the intake opening is covered by a counter plate, the pumped fluid encounters resistance from the counter plate when it is being sucked into the pump. For this reason, the pump cannot be operated unless intake conditions are especially good, and is not suited for high-speed operations, high-viscosity fluids, or transfer of slurries.
With pumps that have a counter plate in just the working oil side space, there is no counter plate covering the intake opening so the problem described above is eliminated. If there is too much working oil in the working oil side space when the pump is started, however, the diaphragm may be excessively deformed. In particular, a section of the diaphragm that abuts the discharge opening can be pushed into the discharge opening, leading to deformation or breakage of this section.
It is an object of the present invention to overcome the defects described above of reciprocating diaphragm pumps that do not have counter plates in the pumped fluid side space.
Another object of the present invention is to provide a reciprocating diaphragm pump that can prevent deformation, breakage, and the like of the diaphragm caused by the diaphragm being pushed strongly against the discharge opening during operation of the reciprocating diaphragm pump and that can also ensure smooth fluid transfer of the pumped fluid.
In order to achieve these objects, the present invention provides a reciprocating diaphragm pump including: a pump chamber divided by a diaphragm into an active oil chamber and a pumped fluid chamber, the pumped fluid chamber not having a counter plate; a pumped fluid intake opening section transferring pumped fluid to the pumped fluid chamber; and a pumped fluid discharge opening section discharging the pumped fluid from the pumped fluid chamber.
The pumped fluid discharge opening section includes means for preventing diaphragm breakage by preventing the diaphragm from entering the pumped fluid discharge opening when the pumped fluid in the pumped fluid chamber is discharged from the pumped fluid chamber.
Diaphragm breakage preventing means can be a disc-shaped body formed with a plurality of small openings mounted in a ring-shaped cavity disposed at the pumped fluid discharge opening.
Diaphragm breakage preventing means can be an opening/closing plate that is normally open and that can open and close the pumped fluid discharge opening using a biasing member.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.